Defending champion Vincenzo Nibali's team Astana is involved in another drug-related controversy on the eve of the Tour de France.
Rider Lars Boom, 29, has failed a health test for low cortisol levels, which can indicate abuse of cortisone.
On its own this is not a doping violation.
But Astana is a member of the voluntary group, Movement for Credible Cycling (MPCC), and under its rules Boom should be stood down for eight days.
That would mean the Kazakh-based team starting the race a rider short as it is too late to call up a replacement.
Astana were told about this test after the deadline for putting in final line-ups and, despite asking the UCI for a late change to replace Boom with Alessandro Vanotti, that request is likely to be declined.
Astana's other option is to ignore the test, withdraw from MPCC and let Dutch rider Boom start the race.
|Team Sky's Geraint Thomas's analysis of all 21 stages of this year's three-week race, which starts in Utrecht on 4 July.|
Only half of cycling's leading teams are members of the group and two other teams have recently quit over the same issue.
But the fallout for Astana will be so much greater after two of its senior riders and three juniors failed anti-doping tests last year.
This led to a drawn-out battle with the sport's governing body, the International Cycling Union, over its licence to compete.
The UCI ultimately backed down but Nibali's team was left in no doubt that another positive test would see them thrown out.
Boom's cortisol test should not trigger that sanction but it will ratchet up the suspicions around Astana.
Cortisol is a steroid hormone produced by the adrenal gland and is important in the control of blood sugar.
Boom, the 2011 Tour of Britain champion, joined the team this year and was set to help Nibali launch his predicted attack on the cobbles of the Tour's fourth stage.
Boom won a similar stage in last year's race and is an expert in the type of racing we should see in the 102nd Tour's technically challenging first week.